Over recent years road networks in many areas have become increasingly congested. A number of technological tools exist to help road users under such difficult circumstances. For example, a combination of UPS technology and map databases makes it feasible for road users to monitor their position in the road network in real time. Such systems can be further enhanced with route calculation algorithms which assist a user in identifying a preferred route from his present location to a specified destination. Such a system is described in US20050209773A1. Such a preferred route may be selected as being the geometrically shortest route, or one which uses a maximum of fast roads, or a compromise of the two so as to provide a predicted fasted route. It is known in the prior art for a vehicle equipped with location equipment such as a GPS receiver and radio telecommunications devices such as a cellular telephone to request navigation information from a central navigation system via the cellular telephone network. This central navigation system will have not only map databases and route calculation algorithms as discussed above, but will offer the advantage over mobile standalone navigation systems that the central map database may be regularly updated so as to take into account road works, accidents etc. affecting routing decisions. By this means better routing information may be provided. US20050027446 describes such an approach.
As will be readily appreciated, the actual time that it may take to travel a particular route may bear little resemblance to a journey duration predicted on the basis of ideal or average conditions. Traffic conditions are a key factor in any real journey duration, in particular in metropolitan areas.
It may be envisaged to augment the prior art system described above so as to receive journey report information from vehicles that have requested navigation information, so as to compile information reflected journey times using different routes through the route network. The system may thus take the historical information thus gathered into account when calculating an optimum route, so as to recommend in preference such routes as have proved in the past to be most rapid.
Traffic conditions generally display cyclic characteristics. The most obvious of these will be rush hour maxima on weekdays, low traffic on Sundays etc. More subtle effects and effects having a longer cycle period such as annual holidays etc may also be noticeable. Where historical information is gathered as described above, an analysis of the collected information may be carried out in order to detect such cyclic effects. A further degree of intelligence may thereby be built into the system, such that recommended routing is optimised for the particular time and date at which the journey in question is to be carried out. U.S. Pat. No. 6,892,131 relates to such an arrangement.